Dr. J. W. Gregory — Some Jurassic Bryozoa. 61 



II, — On some Jurassic Species of Cheilostomata. 



By J. W. Gregory, D.Sc, F.G.S. ; 



of the British Museum (Natural History). 



THE extraordinary abundance of Bryozoa of the order Cheilosto- 

 mata which occurs throughout the Cainozoic era, in comparison 

 with their scarcity in earlier formations, has often been remarked. 

 Interesting explanations of the suddenness of their appearance 

 have, moreover, been offered by those who do not attach so much 

 importance, as do some, to the imperfection of the geological record. 

 Cheilostomata are not unknown from earlier deposits: the Cretaceous 

 system has yielded a fair number, while even as early as the Silurian 

 species have been found. Though doubts have been thrown on 

 these early records, there seems no sufficient reason to discredit 

 them. Even if Prof. Nicholson's Hippothoa inflata (Hall) ^ should 

 turn out to be a Stomatopora, which, if the figure be correct, is 

 most unlikely, there remain many species in later Paleeozoic deposits : 

 such are those belonging to Prof. James Hall's genus Pahscliara,^ 

 which Mr. Ulrich ^ accepts as Chilostomatous, though Pi'of. von 

 Zittel"* includes it doubtfully with the Ptilodictyonidce. Some of the 

 specimens of Lichenalia, etc., figured by Hall,^ as well as the same 

 author's Cyslopora geniculata,^ may also belong to this order. 



The Jurassic fauna, however, so far contains very few records of 

 Cheilostomata, though Prof. Nicholson'' remarks that from the Jurassic 

 onward there are abundant remains of this group. Michelin has 

 figured ^ a specimen which he has named Eschara ranvilliana, which 

 certainly belongs to the Cheilostomata, though until its internal 

 structure is known it cannot be definitely placed. It must be 

 assigned to the suborder " Athyriata " and probably to either the 

 Microporidce or Cellariidcs. The latter is most probable, as species 

 of this family occur on the same horizon in England. Haime' has 

 recorded two species : Terehripora antiqua, D'Orb., which has not 

 been figured, and the description is insufficient to determine the 

 order to which it belongs ; his second species is the Cellaria Smithi, 

 Phillips,^" which he follows Morris ^^ in definitely including in 



1 H. A. Nicholson, Descriptions of Polyzoa from the Silurian Formation, Rep. 

 Geo]. Surv. Ohio, vol. ii. Pakeontology. 1875, p. 268, pi. xxv. fig. 1. The AkcCo 

 iiifiata of Hall, Palseontology of New York, vol. i. 1847, p. 77, pi. xxvi. fig. 7. 



^ James Hall, ihid. vol. vi. Corals and Bryozoa, 1887, e.g. Paleschara dissimilis, 

 p. 35, pi. XV. fig. 11. 



^ E. 0. Ulrich, Palaeozoic Bryozoa, Palaeontology of Illinois, part ii. sect. vi. 

 Geol. Surv. Hlinois, vol. viii. 1890, p. 366. 



* K. von Zittel, Handbuch der Palaeontologie, Palaeozoologie, Bd. I. Abth. I. 

 If. 4, 1880, p. 604. 



5 James Hall, ibid. vol. vi. 1887, e.g. pi. xxx. figs. 5 and 6; pi. xxxi. figs. 12, 17, 

 20, 22, and 29. ^ jjj^^ p_ io3, pi. Ixvi. figs. 7-9. 



'' H. A. Nicholson and E. Lydekker, a Manual of Palseontology, 3rd edit. 1889, 

 vol. i. p. 634. 



8 H. Michelin, Iconographie Zoophytologique, Paris, 1846, p. 243, pi. Ivii. fig. 12. 



^ J. Haime, Description des Bryozoaires fossiles de la formation Jurassique, Mem. 

 Soc. Geol. France, ser. 2, t. v. 1854, p. 217. 



'" J. Phillips, Illustrations of the Geology of Yorkshire. Part I. The Yorkshire 

 Coast, 1829, p. 143, pi. vii. fig. 8. 



" J. Morris, Catalogue of British Fossils, 1843, p. 39. 



